bug#53071: 28.0.90; Emacs 28 regression: incorrect code generation for complex pcase forms?

[Eli Zaretskii]

> From: Mattias Engdegård <mattiase@acm.org>
> Date: Wed, 12 Jan 2022 17:03:44 +0100
> Cc: 53071-done@debbugs.gnu.org, Philipp <p.stephani2@gmail.com>,
>  Stefan Monnier <monnier@iro.umontreal.ca>,
>  Paul Pogonyshev <pogonyshev@gmail.com>
> 
> >>> commit 1362a9fec4dff341a84c881ac17dbf1ee2cf82fd
> >>> Author: Mattias Engdegård <mattiase@acm.org>
> >>> Date:   Fri Mar 5 20:21:01 2021 +0100
> >>> 
> >>>   Make lambda-lifting work again
> >> 
> >> Not that again.  Let's CC Mattias then.
> > 
> > Again? In any case, that change only fixed a typo in earlier code by 
> > Stefan. More likely to be a logic error in the parent change 
> > (a350ae058cae), or in edebug.
> 
> No, you're right, it's bug#51982 again. I've backported the fix from master, 
> which we should have done from the beginning. Paul, I'd like to say on record 
> that listening to you would have saved us much time.

Emacs 28 is in a very good shape, and no serious problems were
reported in several weeks.  We could release Emacs 28.1 in a few
weeks, fingers crossed.

So I'm about to revert this backport, but I'm prepared to hear
arguments why shouldn't I.

>From my POV, the regression is very minor, and it doesn't justify such
a non-trivial change in such a central place.  If you think the
problem is serious, I'd rather revert the change we did which produced
the regression in the first place (assuming it's not too complicated).

Thanks.